Paying The Mothers Doctor Bills

I was with a female and a month later was told by her she was pregnant. during conversation found out she was with another person a couple days after myself. She feels strongly that this child is mine, but how can I be sure until it is born and a DNA test is done to make all fair.

She is being insistant that I help with the bills, but I want to know if I really have too under the circumstances. She is telling me that she won't put my name on the birth certificate or let me see the baby if I don't start help paying the bills.

Is this realistic on her half and I'm being bullheaded OR am I thinking right and won't sent anything until DNA tests are done. What is fair and legally write? She is probably documenting many conversations about this matter and will use this after baby is born.